RADIO FREQUENCY - Post baking drying technique

Biscuit manufacturers all across world have following options to increase capacity in existing plant . They have been trying various method to achieve this .

• Increase the oven length hence increasing moulder /cutting speed .Not all ovens has this advantage you have to check whether another zone can be added to existing biscuit oven or not .

• Run plant at maximum speed with increased temperatures in different biscuit oven zones resulting in reduced baking time .This has disadvantage that the quality of biscuit gets affected.

• Using Radio frequency dryers at the delivery end of biscuit ovens ,this helps in reducing moisture further by 10 - 11% hence we can increase the speed of moulder/cutter resulting higher output .

Principle on which radio frequency dryer work s is that as water has As product exiting the baking oven enters the RF post-baking dryer, it passes through an electrode array having an alternating electric field which reverses its polarity at a rate of 40.68 million times per second.
Water is comprised of "polar molecules" which can be likened to each molecule having a north and south pole. When passing through an alternating electric field, polar molecules react similar to the way bar magnets behave in an alternating magnetic field, constantly realigning themselves to face the opposite pole. At a frequency of 40MHz, friction caused by this rapid movement causes the polar molecules of water to quickly heat, wherever moisture is present, throughout the entire thickness of the product.

Nonpolar materials such as fat, oil, and dry ingredients do not react and, therefore, are not directly heated by RF energy. In the case of bakery products, this means an RF dryer will preferentially heat and dry the wettest area of a product without heating the areas already dry. Typically, there is greater moisture in the interior of a product as it exits a conventional oven. Therefore, this moist area will preferentially absorb more of the RF energy.

Developed for high-volume cookie production Post-Baking Dryers quickly and efficiently remove residual moisture trapped within the center of the product, permitting conventional ovens to run at the maximum speed that a product can be produced with the correct loft, crumb structure, and color. These RF dryers are available in different band widths

Advantages of RF heating
Increased Throughput - Up to 30% increase for crackers and often up to 40% for cookies.

Elimination of Checking - By greatly reducing the moisture variation throughout the thickness of the product, checking caused by differential shrinkage is eliminated.

Excellent Control of Final Moisture Content - Final moisture is controlled to approximately +/-0.25%.

Independent Color Control - Since moisture is controlled in the RF dryer, color development in the oven can be done without concern for final moisture content

Refer radiofrequency.com for more details on RF technology